The present invention relates to an apparatus and method for reducing drag forces at the interface between a liquid and a solid in relative motion between one another. More particularly, the present invention is directed to the use of the surface tension properties of a liquid in conjunction with a specialized solid material to provide an air layer between the liquid and the solid material to reduce friction therebetween.
In the past it has been known that it is desirable to reduce the friction created, for instance, by a boat hull running over water or a liquid flowing through a pipe, whereby the boat may move faster over the water or the liquid may be moved through a pipe with increased efficiency. While it has been known that the imposition of a gaseous layer, such as air, at the interface between the liquid and the solid will reduce friction between the boat hull, for example, and the water over which it is traveling, there remains room for improvement in structures which can provide such a friction reducing layer. In the past many of the methods used were to port air under pressure through relatively large holes in the boat hull to provide an air layer therebetween. While effective when the system was active, during periods of inactivity there was water intrusion into the holes. Thus, provisions had to be made to prevent the intrusion of water or to remove the unwanted water in order to operate the device.
In the present invention, the inventor has discovered that the large difference in the surface tension properties between liquids and gaseous materials can be utilized in a manner such that air may be easily transported to a solid/liquid interface from an air storage area in a way which does not allow liquid to flow back into the air storage area. This improves the efficiency in achieving relative motion between the solid and the liquid and solves the problem of unwanted liquid entering the system.
It is therefore an object of the present invention to take advantage of the difference in surface tension between a liquid and a gaseous material and form a suitable apparatus for imposing an air layer between the solid and the liquid layer to reduce drag forces during relative motion.
In accordance with the present invention there is provided an apparatus and method for reducing friction at the interface of a liquid which has a known surface tension and a solid interface member. The apparatus includes a solid interface member which has a plurality of apertures over its entire surface which is exposed to the liquid. The apertures are of a preselected size and dimension such that the surface tension of the liquid will not allow the liquid to pass through the interface but will allow a gaseous material with less surface tension than the liquid to pass through the apertures. A mechanism is provided for intperposing the gaseous material through the apertures at the liquid/solid interface to reduce the drag forces between the liquid and solid interface which would otherwise result from the relative motion between the liquid and the solid interface member.
Other advantages of the present invention will be readily appreciated as same becomes better understood in light of the following description when taken in connection with the accompanying drawings.